Piston for internal-combustion engines



W. T. BOWERS. PISTON FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED SEPT. 17, I921.

Patented; Dec. 5,1922.

XASVAQQQ Patented Dec. 5, 1922;

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' them 1* ime WILLIAM THOMAS rewrite; or Barrrraonn, ireiarmnn, assrenon. or ONE-HALF 'ro enemas aarraason LEVEY,'OF BALTIMORE, MARYLAND.

PISTON FOR INTERNAL-COMBUSTIQN ENGINES. Application filed. September 17, 1921. Serial No. 501,437.

' I To all whom it may concern.

Fig. 1;

Be it known that 1, WILLIAM THoMAs BowERs, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Pistons for Internal-Combustion Engines; and I do hereby declare the following to be a full, clear, and exact description ofthe invention, such as will enable others skilled in the art to which it appertains to make'and use the same.

This invention relates to pistons for internal combustion engines, and has for its object'to provide a means of packing the pistons which will be inexpensive to con.- struct and more efficient in action than those which have been heretofore proposed.

With these and other objects in view, the invention consists in the novel details of construction and combinations of parts more fully hereinafter disclosed and particularly pointed out in the claims.

Referring to the'accompanying drawings forming a part of this'specification, in which like numerals designate like parts in all the views:

Figure 1 is a longitudinal, sectional view, partially broken away, of a cylinder and piston made in accordance with this invention;

Figure 2 is a cross sectional view somewhat exaggerated, of the parts shown in Figure 3 is a sectional detail view, greatly enlarged, taken on the "line 3-3 of Fig. 1, looking in the direction of the arrows;

Figure 4 is an exaggerated view of one form of spring ringemployed in connection with the piston shown in Fig. 1;

Figure 5 is a perspective view of anothe form of spring'ring employed in connectionwith the piston shown in Figure 1 Figure 6 is an exaggerated v1ew of the spring rings shown in Fig. 5; and I Figure 7 is an elevational view of the piston showing the supporting shoulders and -51 for thecut segments.

p 2 is provided.

pistons and the parts being at a high ternperature the said oil carbonizes said rings and lessens their packing qualities, to such an extent that the piston soon leaks.

In order to partially avoid these disadvantageous results, it has been proposed to split the piston in spirals extending 180 or less around the surface thereof, and in various other Ways, and to then insert inside the split sections aspring ring which will cause the walls of the piston to fit more tightly the interior of the cylinder. Although this expedient is a step in the right direction, yet it is found in practice that the splits in the piston are so short that they leave the walls thereof so stifl' that the fit between the outer wall of the piston and the inner wall of the cylinder is not sufliciently accurate to prevent the piston from again leaking. 9n the other hand, I have found if these said prior slits or splits are extended the segments of the piston will in operation pullout like a I firmly in place by lugs so that it cannot fail to function properly and there are other features of improvement which will appear hereinafter.

Referring to the accompanying drawings, and especially to Figs. 1 and 7 the cylinder is represented by the numeral 1, the piston by the numeral 2, 3 represents the usual metal packing rings, 4: any'suitable lugs or other means for securing the piston rod to the piston, 5, represents the closed head of the piston, and 6 and 7 represent spirally v disposed cuts or slits with which the piston As stated above, the cylinder is worn to agreater or less extent :by the reciprocation of the piston, and this efiect isshowngreatly exaggerated in Fig. 2, wherein the outer wall of the cylinder is illustrated-as cylindrical, Whil? the inner wall 8 therfiQf is. illustrated as of an elliptical shape, due to the wearing of the walls of the piston 2. But the said piston 2 being provided with the pair of parallel spirally disposed grooves 6 and 7, a portion or slit segment 9 of the said iston 2 is capable of being pushed outwar ly by means of the spring 10, so that said segment 9 follows accurately the inner contourof the worn portion of the cylinder 1, and thus makes a tight fit with said cylinder, although the latter may be badly worn. In order that this said'slit segment 9 of the piston shall be the more readily pushed outwardly to fit the cylinder 1, each of the slits 6 and 7 are carried considerably more than 180 around the cylindrical portion of the piston.

That is to say, as will beclear from Figs. 1 and 7,'the slit 7 starts at the lower portion of the piston, or at, say, about 90 to the left of the lugs 4 appearing in Fig. 2, whereupon it extends upwardly and over the outer wall of said piston toward the right, see Fig. 7, and it finally ends up at or near the lug 4 illustrated in full lines in Fig. 1, thus traversing an angular arc of about 270. The course of this slit 7 will also be clear from Fig. 5, wherein one end 16 of the spring 17 covers the starting point of said slit, and the slit then. follows up- .wardly the spiral course of said spring 17 until it reaches the other end 18 of said spring, as is indicated in dotted lines.

In the same way, the spirally disposed slit 6 starts at the lower portion of the piston, see Fig. 7, and extends upwardly from the point 13, as seen in Fig. 5, until it reaches the point 14 located at 180 from said point 13 (see also Figs. 1, 2 and 7), whereupon it passes upwardly around the piston 2 for another distance of about 90, or until it reaches the point 20, see Figs. 5 and 7.

Itrresults from this construction that as the segment or strip 9 which is thus cut from the piston 2 extends substantially 270 around the said piston, it is very flexible, and therefore can be pushed outwardly with a moderately strong spring 10, and especially if said spring is initially formed in an elliptical shape, as is indicated in Fig. 4.

Accordingly, I provide such an elliptical spring 10 and snap it into place, so that the said spirally shaped segment 9 is pushed outwardly from the wall of the piston to form the shoulders 21 and 22, see Fig. 1. Not only are these said shoulders 21 and 22 formed, but the slits6 and 7 themselves are made inclined, as best illustrated at 23 in Fig. 3, so that any oil which is caught on said shoulders 21 and 22 will be drawn down or led into the interior of the piston 2, and

. thus will it be preyented from reaching the packing rings 3. 4

The elliptically formed ring 10 is firmly held in the lugs 25, which are cast on the interior of the piston at about 180 from each other, as will be clear from the drawings. Therefore, it is only necessary to snap t e elliptical spring 10 into place between the lugs 25, whereupon the natural force of expansion will force out the portion 9 of the piston and keep it always in close contact with the interior of the cylinder 1. I

In the somewhat modified form of the invention illustrated in Fig. 5, instead of the single ring 10 illustrated in Figs. 1 to 4, I provide the two rings 17 and 26. Each of these rings are of a flat ribbon like construction bent into a spiral form and are elliptical in curvature instead of circular, as will be clear from Fig. 6.

That is to say, the flat spirally disposed ring 17, for example, extends around the interior of the piston 2 and follows closely the slit 7, as explained above, while the flat spirally curved ring 26 in like manner follows closely the slit 6 in the cylinder 2. But each ring 17 and 26 instead of being spirally curved on a true cylinder are spirally curved on an elliptical cylinder, so that the inherent resiliency of the rings con stantly pushes outwardly slit segment 9 of the wallsof the cylinder 2. But the segment 9 of said walls being more resilient than the other portions, the rin naturally cannot lie absolutely flat against the interior wall of the cylinder 2, and therefore, the oil which leaks through the slits or passages 6 and 7 naturally works its way on the interior of the piston, and thus prevents the said oil from reaching the packing rings 3 and deteriorating the same.

But, as above stated, even when the segment 9 is thus made sufliciently resilient to fit accurately the insides of worn cylinders, I find the parts are liable to separate in a direction longitudinally of the axis of the piston when operating at high speeds and thus give rise to leaks and destroy many of the advantages derived from the foregoing construction.

To prevent this serious objection, I proceed as follows: At the lower ends of the slits 6 and 7, I bore the round holes 45 and 46 respectively. I then, beginning at the bottom edge 47 of the piston, cut the slits 48 and 49 reaching almost to the holes 45 and 46 respectively, and making an angle of about 40 with said edge 47. The metal left between said holes 45 and 46 and the terminal points of said slits 48 and 49 may be cut through with a very fine saw, or it may be forcibly cracked to form a connection having substantially no width between said holes 45 and. 46 and said slits 48 and 49, to the end that there will be found a supporting shoulder 51 on which rests the metal at the termination of the slit 7., and a the inclination of the slits 6 and 7 as illus- 5 48 and 4.9 with the holes 46 and 45 have substantially no width they constitute restrictions, in the slits as a Whole, and said restrictions provide shoulders preventing the segment 9 from moving longitudinally with respect to the pistons axis, and thus prevent said segment from opening out the slits 6 and 7 in such a manner as to permit the piston to leak.

It will now be clear that by following my construction, I am enabled to produce a very resilient segment portion 9 of the piston 2 which, no matter how the interior of the cylinder may wear, is yet pushed outwardly against the interior wall of the cylinder whlle at the same time I prevent said segment from contracting its diameter and causing leaks by reason of its resiliency. I

' therefore am enabled to maintain a tight fit where others have failed.

Further, it will be seen that owing to trated at 23 in Fig. 3, the oil readily flows from the outside of the piston, to the interior thereof, and thus is kept from finding its way to the packing rings 3.

In order to more effectually hold the fiat spiral rings 17 and '26 in place, they are provided with the. cut away portions 30 and 31 respectively, 'which cut away portions fit the lugs 4 on the interior of the piston and thus are the rings 17 and 26 eld in place.

What I claim is:

1. In an internal combustion engine, the combination of a cylinder; a hollow piston in said cylinder having a pair of parallel helically disposed slits through its walls,

each extending more than 180 around said piston to form a resilient helically'shaped segment; and an elliptically curved spring located on the interior of said piston adapted to push outwardly said segment, substantially as describe 2. In an intern-a1 combustion engine, the combination of a cylinder; a hollow piston in said cylinder having a pair of parallel helically disposed slits through its walls each extending more than 225 around said piston to form a resilient helically shaped segment; an elliptically curved spring located on the interior of said piston adapted to push outwardly said segment; and means on the interior of said piston to hold said spring in place, substantially as described 3. In an internal ombustion engine, the combination of a cylinder; a hollow reciproeating piston in said cylinder having a pair of parallel helically disposed slits through its walls, each of said slits in its passage through said walls being inclined to the axis of the piston and each slit extending through an arc of more than 225 to form a resilient helically disposed segment capable of being pushed out from the body of the piston; and a, pair of flat, helically formed and elliptically curved springs: located on the interior of said piston adapted to press against said segment, substantially as described. I

4. In an internal combustion engine the combination of a cylinder; a hollow reciprocating piston in said cylinder having lugs on its interior and a pair of parallel helically disposed slits through its walls, each of said slits in its passage through said walls being inclined to the axis of the piston and each slit extending through an arc of more than 225 to form a resilient helically disposed segment capable of being pushed out from the body of the piston; and a pair of flat, helically formed and elliptically curved springs located on the interior of said piston adapted to press against said segment and having cut away depressions adapted to fit said lugs and to be held in place, substantially as described.

5. The herein described hollow piston for internal'combustion engines having a spirally disposed slit in its walls reaching to the extreme end of said piston, and having a restricted portion in its length to provide a supporting shoulder for severed metal, substantially as described.

6. The herein described hollow piston for internal combustion engines having a pair of spirally disposedslits through its walls, said slits having angularly disposed end portions, and associated with shoulders for supporting the severed metal, substantially as described.

7. In an internal combustion engine the combination of a cylinder; a hollow piston located in said cylinder having a plurality ofspirally disposed slits'through its walls, and each slit provided with a restricted portion to form a supporting shoulder for the severed metal, substantially as described.

In testimony whereof I aflix my signature.

-WILLIAM THOMAS BOWERS. 

